Short-wave radio transmission



1945- G. c. SOUTHWORTH 2,369,80

SHORT-WAVE RADIO TRANSMISSION Filed June 8, 1940 5 Sheets-Sheet l INVENTOR By G.C.$OUTHWORTH A TTORNE V Feb. 20, 1945. SQUTHWORTH 2,369,808

SHORT-WAVE RADIO TRANSMISSION Filed June 8, 1940 3 Sheets-Sheet 2 5; I:20 T -2 T SOURCE |-I F/GJ/ A J 27 sou/ace Feb. 2@, 1945. c. SOUTHWORTH I2,369,8Q8

SHORT-WAVE RADIO TRANSMI S ION Filed June 8, 1940 3 Sheets-Sheet 3 FIG/3FIG. /4

as U as A T TORNE V Patented Feb. 20, 1945 SHORT-WAVE RADIOTRANSIVHSSIDN George Clark Southworth, Red Bank, N. 1., aasigner toAmerican Telephone and Telegraph Company, a corporation of New YorkApplication June 8, 1940, Serial No. 339,559

22 Claims.

This application is in part a continuation of my application Serial No.743,753, filed September 12, 1934, which'issued on July 9, 1940, asUnited States Patent No. 2,206,923.

The present invention relates to the radiation and reception of radiowaves of ultra-high frequency and more particularly to apparatus andmethods for the broadcast or wide angle radiation and reception of suchwaves. It has for a principal object the production of new and improvedapparatus for the radiation and reception of high frequencyelectromagnetic waves.

In accordance with certain embodiments of the invention, electromagneticwaves are generated in a dielectric guide medium and launched from thatmedium into space for radiation in all lateral directions. In someembodiments dielectrically guided waves are established in a vertical,hollow metal pipe guide and radiated therefrom in all horizontaldirections or in a plurality of preferred horizontal directions. Certainembodiments of the invention are featured by the provision of means forenhancing radiation laterally or radially from the open end of a hollowmetal pipe guide. In accordance with certain features of the invention,electromagnetic waves are launched from or received at a point betweenjuxtaposed metallic surfaces defining a radial transmission line orbi-conical structure. In accordance with other features a radiator ofthe latter kind is excited by means of a hollow pipe guide or other waveguidin transmission structure The foregoing various embodiments andfeatures are adaptable also toithe reception of radio waves. Theinvention is further featured in certain aspects by the use ofdielectrically guided waves of symmetric types as will appearhereinafter.

The nature of the present invention and its various objects, featuresand advantages including those mentioned hereinabove, will appear morefully on consideration of a limited number of specific embodiments ofthe invention which have been chosen for presentation in the followingspecification and accompanying drawings. It will be understood that thisdisclosure has relation principally to these specific embodiments andFig. 1 but showing radiation from several sources arranged verticallyone above another; v

Fig. 3 is a diagrammatic vertical section like Fig. 2 but withvariations of diameter of the guide instead of the use of metallic bandsas in Fig. 2;

Fig. 4 shows a dielectric rod with radiation from an end portion ofreduced diameter;

Fig. 5 shows a modification of Fig. 4 in which the non-radiating portionof the guide has a metallic sheath;

Fig. 6 is a diagrammatic vertical section of a radiator excited withsymmetric magnetic waves; and Figs. 7 and 8 show details thereof;

Fig. 9 is a diagrammatic vertical section of a radiator excited withasymmetric electric waves; and Fig. 10 shows details thereof;

Fig. 11 is a diagrammatic vertical section of a radiator excited withasymmetric magnetic waves:

Fig. 12 is a vertical section showing a dielectric guide radiatingvertically in combination with a conical reflector to enhance radiationin all substantially horizontal directions;

Fig. 13 shows a modification of Fig. 12 incorporating a bi-conicalradiator fed from a metal pipe guide;

Fig. 14 is a modification of Fig. 13 showing details for the mechanicalsupport of the elements;

Fig. 15 shows a modification of Fig. 14 and it is illustrative also of amanner of coupling a coaxial conductor line to the bi-conical radiator:

Figs. 16 and 1'7 show a further modification of Fig. 14 that isespecially adapted for the use of waves of H0 or symmetric magnetictype; and

Fig. 18 shows another form of bi-conical structure especially adapted asa radio aid to the blind landing of aircraft.

In my application, supra, in my U. S. Patents 2,129,711 and 2,129,712,both issued September 13, 1938, and elsewhere, it has been shown thatelectromagnetic waves can be propagated through dielectric rods andhollow metal pipes under certain circumstances of wave frequency,di-electric constant and electromagnetic field configuration. It hasbeen shown and explained that there are various types of wavessusceptible of propagation in the so-called di-electrically guided form,each type being identified by the characteristic spacial distribution ofits component electric and magnetic fields. Certain types have beenclassified as magnetic, others as electric, and there has been a furthersubdivision of type into symmetric and asymmetric. Thus We shall haveoccasion hereinafter, as in the patents identified above, to

refer to dielectrically guided waves of symmetric magnetic type, forexample, which may be alternatively designated mathematically as Ho.Inasmuch as those skilled in the art are now familiar with the natureand characteristics of dielectrically guided waves and of the severalwave types in particular, and of means for launching and receiving eachtype of wave, such matters will not be treated in detail herein butreference may be had to the literature of the art and to my priorapplication and patents. For the purposes of the present application thephrase "dielectrically guided waves" appearing in the. appended claimsmay be understood as denoting wave transmission of the kind described.characterized in that the guiding structure presents to the waves thetransmission characteristics of a high-pass filter the cut-oi! frequencyof which is functionally related to a transverse dimension of theguiding structure.

. Referring now to Fig. 1 there is represented an ultra-high frequencywave source I that is connected to the lower extremity of a coaxialconductor transmission line comprising a cylindrical outer conductor 2and an inner axial conductor 3. At the upper extremity of the coaxialconductor line the inner conductor 3 is expanded into a cone I and thecylindrical outer conductor 2 is expanded into a corresponding funnel 4,the cone and the funnel 4 being spaced apart and this space being acontinued expansion upward of the space between the conductors 2 and 3.In a horizontal section at any height a constant ratio is maintainedbetween'the radius of the 'outer surface of member I and the radius ofthe inner surface of member 4.

The cone 5 has a flat metallic base I on top. and in the same planetherewith it is surrounded by a flat annulus 8, the'central portion 1and the flat annulus 0 being spaced by an annular gap 8. It will readilybe seen that the lines of force which extend radially between theconductors 2 and 3 will pass up between the flaring members 4 and l andwill arch across between the plates I and I, as indicated in Fig. 1. Allof the lines shown in Fig. 1 are electric lines of force: generally themagnetic lines are circles around the vertical axis of the coaxialconductor system 2-3. Standing on the plates or electrodes 8 and l is acylinder 8 of dielectric material. This may be regarded as a shortsection of cylindrical dielectric guide with vertical axis. Surroundingthe base of the dielectric guide 9 is a conductive platform ll.

The waves in the dielectric guide -9 represented by the lines ofelectric force are broken oil in loops and progress upwardly therein.These waves will be recognized as being of the symmetric electric type:electric, inasmuch as there is a component of electric force in thedirection of propagation, and symmetric inasmuch as the field is uniformin all horizontal directions around the axis of propagation. These linesof electric force extend out into the space surrounding the guide 9 andform completely closed loops. The latter move out horizontally as wellas upwardly and are detached as electromagnetic waves and radiated intospace. It should be understood that the field represented by the linesof force in Fig. 1 is symmetric about the axis of the u de 9.

Generally the velocity of propagation in the material of the guide 8will be less than in air or empty space. By a proper choice of diameterand dielectric material, this velocity may advantageously be made aboutone-half that of ordinary light. This means that the wave-length in theguide is one half that in the surrounding medium. A specific set of datagiving satisfac tory results is to employ an operating frequency of 1750megacycles per second and to make the guide 9 of an insulating materialhaving a dielectric constant of about 10 and hence an index ofrefraction of about 3.16. The wave-length in the guide depends upon boththe diameter and the index of refraction. The diameter of the guide 9 ischosen at 6.54 centimeters so that the wave-length in the radiator shallbe about one half that in thesurrounding medium. The length or height ofthe cylinder 9 is about 4.5 centimeters which is slightly more than onehalf the wave-length in the dielectric.

The apparatus of Fig. 2 differs from that of Fig. 1 principally in thatthe cylindrical dielectric guide 9 with vertical axis has been muchextended in a vertical direction and surrounded with a metallic band 12at its base and other metallic bands l3 equally spaced along its height.As the waves represented by the lines of force within the guide 8progress upwardly therein, part of their energy is radiated into thesurrounding space between successive metal bands l2 and I3 as indicatedin Fig. 2. The waves then move up to a position where the ends of thelines of force rest entirely on a metallic band such as l3 and in thisstage there is no radiation in the immediately surrounding space. Thenat the next stage higher up between the next two successive metallicbands l3, there is more radiation, and so on. Outside of the guide thelines of force become detached and link end to end to form the wavefront, which presently straightens out vertically and moves radiallyoutward from the guide. As in Fig. 1 the radiation is Q uniform in allhorizontal directions from the guide 9.

Assuming that the material and the dimensions are so chosen in Fig. 2that the wave-length in the guide is half that in the surroundingmedium. then the radiating portions between the metal bands l3 will bespaced at intervals equal to the wave-length in the guide. Thus theywill oscillate in the same phase as indicated by the arrows in Fig. 2.The dielectric material within the guide 9 may be gaseous instead ofsolid if suitable means are provided for supporting the metal bands 3.Appropriate supporting means are described hereinafter with reference toFigs. 14, 16 and 1'7.

Instead of suppressing radiation at points along the height of the guide9 by means of metal bands I: as shown in Fig. 3, this efiect may beattained as shown in Fig. 3 by spaced enlargements of the guide. Withineach enlarged part IS, the lines of force are closed within the guide,but within each reduced part they break out into the surrounding spaceand break off and link together end to end to give the radiated waveconfiguration indicated by the lines of electric force.

Where the diameter is increased as at l5, this has the eflfect ofreducing the speed of propagation along the guide which requires theradiating parts of the guide to be brought nearer together.

In the modification of the invention shown in Fig. 4 a dielectric rod I6is provided to convey the wave to the radiating portion I1. The rod I 8is of such diameterthat the wave energy is largely confined within it,while the radiator portion I1 is also a dielectric rod, constituting anhance horizontal directivity. The waves launched into the guide It atits lower extremity may be symmetric electric waves or of any otherdesired type.

Fig. shows a modification of Fig. 4 in which .the dielectric rod I9 isreplaced by a dielectric rod i9 having ametallic sheath i9. Because ofthe presence of the sheath I9 the diameter of the guide portion ll maybe reduced relative to that of guide I! in Fig. 4 and as illustrateditis of the same diameter as the radiator extension portion il. a

Whereas the combination shown in Fig. 1 is designed for the use ofsymmetric electric waves, the combination shown in Fig. 6 is adapted foruse with symmetric magnetic waves. The principal difl'erence instructure lies in the coupling element 20 that is interposed between theend of the coaxial conductor linev 2-3 and the dielectric radiating rod9. Details of one form which the coupling element 20 may take are shownin Figs. 7 and 8. As will appear from the latter figures the couplingelement comprises a striplike conductor arranged roughly in a figure 8and substantially coplanar, with the upper tensi y. in two oppositehorizontal directions in the plane of the conductors 29 with nullintensity at right-angles thereto. The same radiation of power measuredin watts will give much more intensity in a preferred direction and itsopposite than when the same power is distributed uniformly in allhorizontal directions. If the same power is radiated in both cases, thegain in the preferred direction with the characteristic described isabout three decibels. This means that one watt of power is as effectivein the preferred direction as two watts would be when crossing branch 22of the figure 8 connected to the projecting end of the inner conductor 3of the coaxial line and with the other crossing branch 2i interrupted byand connected to the end of the outer conductor 2. The structureprovides virtually a circular conducting path for the uni-phase flow ofthe exciting current. radiating element 9 of Fig. 6 is about 60 per centlarger than the corresponding element of Fig. l for the same dielectricmaterial and the same wave frequency. v

It will be understood that the. waves traveling up the coaxial conductorsystem 2-9 of Fig. 6.

with the lines of electric force radially directed. are reshaped by thecoupling member and enter the dielectric guide 9 with the lines ofelectric force in the form of horizontal circles. From the guide 9 thewaves are radiated out laterally into space with substantially uniformintensity in all horizontal directions.

For the radiation of waves of asymmetric electric or E11 type, twoparallel conductor rods 23 are extended vertically upward from thesource I as shown in Fig. 9. A high frequency alternating current isimpressed across these conductors at their lower ends. At their upperends they are terminated by the two plates or electrodes 24 and 25having the shape shown in Fig. 10. The lines of electric force extendbetween these plates and some lines also extend across from eachelectrode 24, 25 to the annular base plate 26. Thelines of force becomedetached and progress upwardly and expand laterally and spread outhorizontally with the usual velocity of light in free space. Theconfiguration of the electromagnetic field within the dielectric rod 9is such as to suggest an analogy to the case of two ordinary linearantenna elements standing vertically at the two plates 24. 25 spaced onehalf wave-length apart and oscillating in opposite phase.

The horizontal intensity diagram for the system of Figs. 9 and 10 showstwo maxima of in- The radiated uniformly in all directions. The antennaof Figs. 9 and 10 is very useful when it is desired to avoidinterference with stations in lateral directions by suppressingradiation in those directions. The units of Figs. 9 and 10 can becombined in arrays, in the light of the analogy noted. to give enhanceddirectional selectivity.

Radiation of waves of asymmetric magnetic or Hn type may be effected bythe system shown in Fig. 11. Here the source I puts a high frequencyalternating-current across the two parallel conductor rods 29 whichdiverge at their upper ends and are connected to two diametricallyopposite points ofthe horizontal conductor annulus 21. The lines ofelectric force extend substantially parallel with the diameter of theannulus that connects the upper ends of the two conductors 29. Theselines of force are propagated upwardly in the dielectric guide 9 andoutwardly therefrom with a wave directivity pattern-substantially thesame as that obtaining with the Fig. 9 system. It should be noted thatFig. 11, like Figs. 6 and 9. represent unitary radiators and that theymay be incorporated in multiple structure in the manner illustrated inFigs. 2 and 3. p

Where a dielectric guide comprises a metallic sheath, I have found thatdielectrically guided waves advancing through thepipe toward the openend are radiated therefrom with reasonable emciency and that thedirectivity or field intensity pattern produced depends on the type ofguided wave employed. I have found too that guide comprising a. metalpipe 30 of circular cross-section containing only an air dielectric. Atthe lower extremity of the pipe 90, means (not shown) are provided forlaunching therein dielectrically guided waves of symmet ic type, suchfor preferred example as symmetric magnetic (H01). or symmetric electric(E01), which advance upwardly through the pipe to the open end shown.Axially aligned withthe pipe 30 and inverted above it is a conicalmetallic member 3|. At the open end of the pipe 30 the guided waves areradiated outwardly with the wave power largely concentrated in thehorizontal plane or approximately so. The directional pattern depends inpart on the directional characteristic of the open-ended pipe 30 and inpart on the reflection efi'ect arising at the conical member 3i. hencethe pattern depends also on the shape and relative position of themember 3|. The direction of polarisation'of the radiated iield dependson the typeof guided wave employed. but in any case it is well knownthat the distant radio wave receiver should be'so oriented withreference to the wave as to yield a maximumreceived signal.

A preferred embodiment of the invention, closely related to P18. 12, isshown in simplified Y form in Fig. 18. This embodiment is. or may be,

the same as that described with Fig. 12 with reference to the followingmodifications. First, the upper extremity of the pi e guide II isterminated in a downwardly extending frusto-conical flange.

32; second, the strictly conical element ii of Fig. 12 has been replacedby a semi-conical member 33 that is flatter and that is somewhat concavesons to better cooperate with the flange 12 to enhance the desiredlateral directivity of the combination.

It will be seen that the members a and a of Fig. 13 form anoutwardlydirected horn having circular symmetry about the axis of thepipe guide It and that the horn so formed is excited approximately atits center by means of the pipe guide 30. In one aspect therefore, Fig.13 may be understood as showing a substantially bi-conical horn havingcircular symmetry as described and a specific kind of exciter fortransferring wave energy to and from the horn. Again, the proportionsand spacing of the members 32 and 32 may be varied within wide limits toyield the precise directivity pattern desired.

Mechanical details appropriate for the support enough torequireadditional structural strength.

Guy wires 39 may be attached to the pipe 30 as shown.

In accordance with a further feature of the invention as illustratedalso in FIG. 14, the wave guiding structure It may have one or moreperipheral gaps spaced apart in the manner and for the purposesdescribed with reference 'to Fig. 2. Each such gap may be provided witha pair of conical flanges 34 forming a bi-conical horn. Greater verticaldirectivity is obtainable by increasing the number of radiating orificesin the array, and it is therefore possible in any case to avoid the useof horns having a high degree of directivity but dimensions so great ato present serious difllculties in providing adequate mechanicalsupport.

Another means of supporting the upper conical member 35 of Fig. 14 isshown in Fig. 15. In this case the upper end of the metallic pipe guide30 is terminated in a slightly flaring portion 40 which at its upperextremity carries the lower conical member 32. At the upper end of theflaring portion 40 there is wedged an insulating disc or washer 4|, andin the central aperture thereof is wedged the vertical tapering metallicrod 48.

The upper portion of rod 43 extends through the vertex of the conicalmember 35 and its end abuts a. metallic cover plate 42 that closes theotherwise exposed top of member 38. Additional anchorage for thesupporting member 43 may be provided in the form of an insulator disc 44near the lower extremity of rod 48. Rain and snow are excluded from thewave uiding system by means of a dielectric cover 45 surrounding the rod48 and coverin the upper end of flaring portion 40. The combinationshown in Fig. 15 as above described is especially adapted fordielectrically guided waves of the symmetric electric type, for

the transition of dielectrically guided waves of such type in the guideto the coaxial extension thereof formed by members 40 and 43 is an easyand emcient one. The supporting rod 43 may be made of a dielectricmaterial rather than of metal, if desired, in which case symmetricmagnetic guided waves may be used, although even with this type of wavethe rod may be of metal if it does not occupy W much of the totaldiameter. Where the support is of metal and symmetric electric waves areemployed as described, they are converted at the lower end of rod 43into coaxial conductor waves and as such they are transmitted to thehorn members. 32 and 38. These waves are then conveyed radially outward,with the members 82 and constituting virtually a flaring radialtransmission line, and they .are radiated uniformly in all horizontaldirections from the periphery ,of the line so formed.

Whereas all of the devices herein described are adaptable to use asradio wave receivers on substitution of an appropriate receiver for thesource I, it is especially evident in the case of Fig. 15 that avertically polarized wave impinging-from any direction on the peripheryof members 82 and 35 will establish coaxial conductor waves betweenmembers 43 and 40 which will then be converted into symmetric electricwaves at the lower end thereof for transmission to the receivingapparatus at the base of the pipe ill.

In lieu of the supporting structures shown in Figs. 14 and 15, thearrangement shown in Figs. 16 and 17 may be employed. The latter isespecially adapted for the use of guided waves of symmetric magnetictype. In Fig. 16 the conical members 32 and 35 are separated and theupper one supported by a plurality of vertical, radiallydirectedmetallic vanes or partitions 46, which extend from the periphery ofmembers 32 and 85, horizontally over the top of the flaring guideportion 40, to a point just short of the axis. Where symmetric magneticwaves are transmitted through the guide 30, the electric field betweenthe members 32 and 35 is horizontally polarized and symmetric about theaxis so that the partitions 48 lie in equipotential regions andtherefore do not disturb the outward progress of the waves. If symmetricelectric waves are used on the other hand, the partitions 48 lieparallel to the electric fleld of the issuing waves, but a substantiallyuniform radiation pattern can be obtained nevertheless in this case bytreating each of the compartments bounded by adjacent members 46 and theconical members 32 and 35 as a metallic horn and proportioning theparameters of each such horn to give the desired distribution of fleldintensity over a given fraction of the angular range to be covered. Inview of the foregoing it will be evident that the vanes 46 can be usedin the same manner in connection with the bi-conical horns of Fig. 14and the spaced metal bands l3 of Fig. 2.

' It is important to note with regard to Fig. 16 that the flaringextension 40 of the pipe guide 30 functions not only as a feeder butalso as a horn. It introduces an initial gradual expansion of theelectromagnetic fleld comprising the guided waves and the furtherexpansion is effected in the bi-conical structure which is arranged as ahoriascasoa 8 zontally directed continuation of the vertical hornportion. Accordingly, for a given degreeof field expansion a smalleriii-conical horn structure is required where a horn-like feeder isemployed.

Another form which the radial transmission I line or bi-conical horn maytake is shown in Fig.

18 in its application to the blind landing of aircraft. Buried in thelanding area, so that its upper extremity is flush with the groundlevel, is a first inverted conical metallicmember 48, and above it andaxially aligned therewith is a second similar member 49 of lesserconical angle, the two members 48 and 49 thus defining a biconical horn.Between the vertices of the two* cones is connected a high frequencyelectromagnetic wave source 50 the waves from which are guided out tothe periphery oi the horn and radiated into space at a predeterminedangle relative to the horizon. Covering the mouth of the horn is agrating 5| made up of metallic rods that are coaxial with the horn.These rods are at right-angles to theelectric fleld'emanating from thehorn and hence do not interfere with propagation and radiation of thewaves. To support the grating 5| and the material above the member 49,radial supporting rods or beams not shown may be provided just belowground level. Alternatively metallic vanes 46 as in Fig. 16 may beinserted between members 48 and 49 to provide the necessary mechanicalsupport.

The lower conical member 48 may be periorated to allow rain water andsnow to fall into the drainage space 55 below it for discharge throughthe drain 52. Above the drain is indicated a manhole 53 through whichthe central portion of the conical members within the annularoverlapping joints 54 may be removed when servicing of the source 50 isnecessary. It will be understood that the combination described radiatesa wave having no lateral directivity but substantial verticaldirectivity so that a plane arriving from any direction and provided ofcourse with suitable guiding equipment can glide down 45 the radiatedwave to a safe landing. It will be further understood that wherehorizontal directivity is required or desired, space between the conesmay be divided by vertical septa into a plurality of hom-like portionsonly some of which are operative, or that individual sources andindividual horns difierently oriented may be substituted. As in all ofthe embodiments hereinbefore described, signals may be impressed on thewaves generated by the source either for communication of intelligenceor merely to distinguish the combination from other radio transmitterswithin the receiving range of the plane apparatus.

It is to be understood further that the embodiments herein disclosed arepreferred illustrative embodiments and that the invention is susceptibleof application in other and varied forms within the spirit and scope ofthe appended claims.

What is claimed is:

1. A radio antenna system comprising means defining a pair of conductiveexpanses juxtaposed and shaped to form between them a wave guidingpassage that extends from an inner end in 7 all azimuthal planes to anouter end that is open 4 to free space for the radiation or interceptionof radio waves, one of said conductive expanses having an opening nearthe said inner end of the passage, and translating means coupled throughsaid opening in radio wave energy transfer relation with said passage.

2. A radio antenna system including means defining a pair of conductivesurfaces spaced apart and forming between them a nared wave guidingpassage that extends in all azimuthal planes from an inner end to aperipheral outer end open to free space for the radiation orinterception of radio waves, one of said surfaces havm ing an openingtherein at the inner end of said passage, and radiowave translatingmeans coupled to said passage through said opening.

3. In combination, a radial transmission line for electromagnetic wavescomprising means defining a pair of juxtaposed conductive expanses eachwith substantial symmetry about a common said transmission line flaringoutwardly from the axial end thereof, one of said conductive expanseshaving an aperture at the axial end of said line, and translating meanscoupled to said line through said aperture for exciting said line or forreceiving radio waves intercepted thereby.

4. Aradio antenna-system comprising means defining a pair of conductiveexpanses juxtaposed and shaped to form between them a wave guidingpassage that extends from an inner end in all azimuthal planes to anouter end that is open to free space for the radiation or interceptionof radio waves, and a transmission line coupled to said passage andcomprising a tubular conductor for the transmission of waves through theinterior thereof, said tubular conductor opening into said passage nearthe said inner end thereot.

5. A system in accordance with claim 4 in which said conductive expanseslie wholly on opposite sides oiv a plane passing between them.

6. A system in accordance with claim 11 in which said transmission lineis a uniconductor wave guide.

40 7. In combination, a pair of juxtaposed conductive surface memberseach defining an at least approximately conic surface, said membersbeing spaced apart with said surfaces in axial alignment to form anelectromagnetic wave guiding passage between them, one of said membershaving an opening therein at the axial end oi said passage, a shieldedtransmission line coupled to the axial end of said passage for launchingelectromagnetic waves therein ior radiation from 50 the other end ofsaid passage or for receiving radio waves entering said other end. saidline comprising a tubular conductor the interior of which. is connectedthrough said opening in communicating relation with said passage.

8. A radio antenna system comprising a conductively sheathed dielectricguide with vertical axis and open upper end, a source or receiver ofradio frequency electromagnetic waves coupled to said guide, anoutwardly extending flange around said open end and an at leastapproximately conical reflector inverted above said open end whereby theradiation pattern of said antenna, system is principally directed in asubstantially horizontal plane.

9. In combination, a hollow pipe guide for ultra-high frequencyelectromagnetic waves, said 4 guide having one end open for theradiation or reception of radio waves, conductive means defining a.transmission line that extends outwardly o from said guide on all sidesthereof and that istransfer relation with the waves in-said guide.

.from.said axial end to the peripheral end thereof, and said translatingmeans comprising atubular conductivewave guide.

12. In combination, a vertical hollow pipe guide the upper end of whichis flared as a vertically directed horn, and a substantially bi-conicalhorn surmounting the said vertically directed horn for the radiation orreception of radio waves in substantially the horizontal plane, thelength of said vertically directed horn being at least several times thewave length of said waves.

' 13. In an ultra-high frequency broadcast antenna system, a wave guidecomprising a conductive, pipe enclosing a dielectric medium,electromagnetic wave translating means for launching into said pipe orreceiving therefrom dielectrically guided waves of symmetric type havinga frequency above the cutoif frequency of the guide, said pipe beingopen-ended, and means at the open end for modifying the radiationpattern of the open-ended pipe.

14. A broadcast antenna system in accordance with claim 13 in which saidmodifying means comprises a conductive horn.

15. In combination, a hollow pipe guide one end of which is open; meansremoved from said open end for launching in said guide or receivingtherefrom dielectrically guided electromagnetic waves of symmetric type.and means defining an approximately conical conductive surface invertedover and spaced from said open end for enhancing the directivity.

16. A combination in accordance with claim 15 comprising an externalconductive flange surmounting the said guide at its open end.

asoaaos 17. In combination, a vertical hollow pipe guide the upper endof which is electrically open, means removed from said open end forlaunching into said guide ultra-high frequency electromagnetic waves ofsymmetric type for transmission to said open end, and means providing aconductive surfor impeding radiation of said waves in a verticaldirection, whereby radiation in the horinontai plane is enhanced.

18. A combination in accordance with claim 17 comprising in addition anexternal conductive flange surmounting the said upper end of said pipeguide. said flange and said conductive surface constituting atransmission line for guiding said waves outwardly from said pipe guide.

19. In combination, a tubular uniconductor wave guide, and translatingmeans for launching or receiving dielectrically guided waves therein,said tubular guide having a, plurality of openings longitudinally spacedapart for the interception or radiation of electromagnetic waves. eachof said openings being substantially continuous circumferentially ofsaid guide and said openings being spaced in such relation to the lengthof such waves as to enhance the directivity.

20. A combination in accordance with claim 19 in which said guide isopen-ended.

21. A combination in accordance with claim 19 including a bi-conicalhorn at each of said openings.

22. A vertical hollow uniconductor guide for the transmission ofdielectrically guided waves therein, a substantially bi-conical hornsurmounting the upper end of said guide for the radiation orreception'of radio waves in the horizontal plane, and means supportingthe upper member of said bi-conical horn comprising a rod anchoredwithin said guide and extending axially through said ripper end.

GEORGE CLARK SOUTHWORTH.

